Technology offers the consumer many choices in communications hardware, allowing both data and voice transmission. These choices include portable computers with internal modems, hands-free speakerphones, landline telephones, and cellular telephones.
Modern portable computers may be equipped with an internal modem and data access arrangement that allows the internal modem to be connected through an RJ-11 connector to the Public Switched Telephone Network. Examples of this technology include portable computers manufactured by Zenith and NEC. These portable computers generally include a speaker used for call progress monitoring; and this speaker is used strictly as an analog output device. The internal modems are used only for sending and receiving modulated digital information through the public switched telephone network. Methods of modulation include the Bell 212, Bell 103 CCITT V.21, CCITT V.22 and CCITT v.22 bis standards.
Hands-free speakerphones can be found in many offices and homes. Generally, these speakerphones are used as an adjunct to a classical telephone which consists of a cradle and handset, and these speakerphones are used for analog voice communications over the public switched telephone network. Digital switching techniques are sometimes used within the speakerphone circuits to prevent analog feedback from microphone pickup of the speaker output.
Cellular telephones as currently manufactured by Motorola (USA), OKI (Japan) and others consist of a radio transceiver unit (TRU) and a control unit (CU), analogous to the cradle and handset of a conventional landline telephone. The transceiver unit is connected to the control unit with numerous wires, these wires transferring the analog information as in a conventional landline telephone, and also transferring digital information not used in a conventional landline telephone. This digital information may contain key press, display, and monitoring information, as well as cellular call set-up instructions. An example of this digital and analog connection can be found in AMPS based cellular telephones, as well as other functionally similar specifications. A complete description of the AMPS system is provided in "The Bell System Technical Journal", 1979, V.1 58, No. 1, pages 1-269. Cellular phones may also provide a hands-free speakerphone, similar to speakerphones available for landline phones.
Landline and cellular telephones generally provide means of indicating to the user their current operating state. For example, when a key is pressed, an audible tone is heard, providing audio feedback, or, when an incoming call is sensed, an audible tone (RING) is heard.
There have been attempts in the prior art to combine some of the devices described above. For example, the addition of a modem to a cellular phone and means for controlling a cellular phone was disclosed by the present inventor in his U.S. Pat. No. 4,697,281. Although this patent provides for modem, transceiver unit and control unit analog and digital control, it does not provide a method for connecting numerous communication devices selectively to both land line and cellular telephone networks.
U.S. Pat. No. 4,718,080 shows a device which connects a standard landline telephone or modem to a cellular car phone, while U.S. Pat. No. 4,578,537 shows an interface which may connect a personal computer, a speakerphone, and a modem to one or more landlines. As a final example, U.S. Pat. No. 4,685,123 teaches a method of adapting one or more telephone lines for either data or voice communications.
None of these known devices or methods succeeds in achieving the functionality ultimately possible from the combination of a modem, portable computer, cellular phone, speakerphone, headset, and landline connection. Were these devices combined within a compact, portable package, the user could use the computer, transmit data, and/or place a cellular voice call, using speakerphone or headset, from any location served by a cellular network. Further, the user could bring the unit into home or office and connect it to the public switched telephone network. With both cellular and landline connections available, the user could place two calls at once, transmitting voice or data over either line. Significantly, the portable computer could initiate all these operations under program control. If all these devices could be combined in an integrated unit so that any pair of devices could function together, the result would be an uniquely valuable business and personal tool.
Prior to the invention disclosed herein, this combination was not conceived of in the art for a number of reasons, but primarily because the devices described were considered to be incompatible. For example, as explained in the inventor's prior U.S. Pat. No. 4,697,281, an ordinary modem loses data during cell handoffs when operated over a cellular link. As another example, ordinary telephones do not provide the correct control signals to place calls on the cellular network, and cellular control units cannot be used as landline handsets. Thus, an integrated portable unit which combines a personal computer, cellular transmitter, modem and speaker phone with headset, cellular control unit, and land telephone connections could not be implemented by merely wiring known devices together.